In the previous funding period, these workers have identified the molecular basis of four inherited forms of salt wasting with hypokalemic alkalosis and diminished blood pressure: Gitelman's syndrome,. Bartter's syndromes type I, type II and type III. In addition, they have mapped tow genes causing the Mendelian form of hypertension pseudohypoaldosteronism type II. They have collected a very large cohort of patients with these disease and in the current project will investigate the genes and phenotypes in these diseases. Specific Aim 1 will determine the spectrum of mutations in these genes in patients with Gitelman's and Bartter's syndromes. These studies will characterize functional domains of these proteins and will also identify specific mutations in families that can be used to track disease alleles through individual kindreds. These studies will also permit comparison of clinical phenotypes arising from mutations in different of these genes. Moreover, they will identify kindreds in whom no mutation is present, providing opportunity to identify new blood pressure-altering genes. Finally, these studies will provide clinical substrate for investigation of extended families of index cases who inherit 0, 1 or 2 copies of mutant genes. Preliminary results demonstrate effects of these genes on blood pressure, calcium homeostasis and bone density. Furthermore clinical studies will determine the impact of inheritance of homozygous of homeostasis, bone density and response to diuretics. Using families that are unlinked to known genes, they will also perform analysis of linkage to attempt to identify new genes causing these phenotypes. Finally, they will pursue the positional cloning of the genes for PHAII.